Inflation control apparatus for an automatic blood pressure gauge

Abstract

An automatic blood pressure measuring device includes a flexible inflation system which quickly and accurately inflates neonatal, pediatric and adult cuffs without significant pressure overshoot. The device uses an electric pump having two intake orifices. A restricted orifice provides air to the pump for all cuff sizes. An unrestricted orifice, which may be opened or closed by actuating a valve, provides air to the pump only when an adult or pediatric cuff is being used. In addition, the pump is controlled by a motor controller which provides dynamic breaking to stop the pump quickly when the threshold pressure has been reached. An overpressure mechanism, separate from the pressure sensor that controls the pump, removes operational power from the pump when a predetermined cuff pressure level, greater than the threshold pressure, has been reached.

The invention claimed is: 
     
       1. An inflation system for automatically pressurizing one of at least two blood pressure cuffs of respectively different sizes with a fluid, comprising: at least two blood pressure cuffs of respectively different sizes;   an electric pump means having an input port for receiving said fluid and through which said fluid is provided to said electric pump means and an output port through which said fluid is provided from said electric pump means to a selected one of said at least two blood pressure cuffs which is coupled to said output port of said electric pump means;   first orifice means, including a first fluid communication path coupled to said electric pump means for limiting the fluid flow provided by said electric pump means to said selected blood pressure cuff so that it does not exceed a first rate;   second orifice means, including a second fluid communication path coupled to said electric pump means for limiting fluid flow provided by said electric pump means to said selected blood pressure cuff so that it does not exceed a second rate, greater than the first rate;   means for determining a desired inflation rate for the selected blood pressure cuff and providing a control signal in response to said determination; and   valve means located in said second fluid communication path and responsive to said control signal for selectively blocking said second fluid communication path so as to cause inflation of the selected blood pressure cuff with said fluid at substantially the first rate or the second rate depending on which one of said at least two blood pressure cuffs of respectively different sizes is coupled to said electric pump means.   
     
     
       2. An inflation system according to claim 1 wherein: the electric pump means includes first and second terminals thereon for applying an operational power signal to the electric pump means; and   the inflation system further comprising:   pressure measuring means coupled to and in fluid communications with said selected blood pressure cuff for emitting an output signal when the selected blood pressure cuff is pressurized to a predetermined pressure level; and   motor controller means, coupled to the electric pump means and responsive to the output signal of the pressure measuring means, for coupling a low resistance path between the first and second terminals of the electric pump means in response to the output signal, to produce a dynamic braking effect in the electric pump means caused by a back electromotive force generated thereby, said dynamic breaking effect assisting the electric pump means to rapidly cease its pumping operation.   
     
     
       3. An inflation system according to claim 2 wherein the motor controller means further includes means for controlling the operational power signal applied to the electric pump means to ensure that a current component of the operational power signal does not exceed a predetermined threshold value. 
     
     
       4. An inflation system according to claim 2 further comprising: further pressure measuring means coupled to and in fluid communication with said selected blood pressure cuff means for emitting an overpressure output signal when the selected blood pressure cuff is pressurized to an overpressure level greater than a predetermined maximum pressure level; and   means coupled to the motor controller means and responsive to the overpressure output signal for disconnecting operational power from at least one of the first and second terminals.   
     
     
       5. A system for automatically inflating a blood pressure cuff with a fluid to a predetermined pressure level, comprising: a blood pressure cuff;   electric pump means, having first and second terminals which selectively receive an operational power signal, and a fluid flow path coupled between a fluid reservoir, said pump, and the blood pressure cuff for providing fluid to inflate the blood pressure cuff coupled thereto when said operational power signal is received by the first and second terminals of the electric pump means;   pressure sensor means, coupled to and in fluid connection with the blood pressure cuff, for providing a pressure signal indicating when fluid in the blood pressure cuff has reached said predetermined pressure level; and   motor controller means, coupled to the first and second terminals of the electric pump means and responsive to the pressure signal, for coupling a low resistance path between the first and second terminals of the electric pump means when the pressure signal indicates that said predetermined pressure level has been reached, to produce a dynamic braking effect in the pump caused by a back electromotive force generated thereby, said dynamic breaking effect assisting the electric pump to rapidly cease its pumping operation.   
     
     
       6. A system according to claim 5 wherein the fluid flow path of the electric pump means includes an intake port coupled to and in fluid connection with the reservoir of said fluid and an output port coupled to and in fluid connection with the blood pressure cuff, the system further including: a first fluid flow orifice, coupled to said electric pump means, limiting the fluid flow to the blood pressure cuff at a first rate;   a second fluid flow orifice, coupled to said electric pump means, for limiting the fluid flow to the blood pressure cuff at a second rate, greater than the first rate;   valve means, coupled to the second fluid flow orifice and responsive to a control signal, for selectively blocking fluid flow through the second fluid flow orifice; and   control means, responsive to operator commands, for generating the control signal and thereby determine the flow rate at which fluid is supplied to the blood pressure cuff.   
     
     
       7. A system according to claim 5 wherein the motor controller means further includes means for controlling the operational power signal applied to the electric pump means to ensure that a current component of the operational power signal does not exceed a predetermined threshold value. 
     
     
       8. A system according to claim 5 further comprising: further pressure sensor means coupled to the blood pressure cuff for emitting an overpressure output signal when the cuff is pressurized to an overpressure level greater than a predetermined maximum pressure level; and   means coupled to the motor controller means and responsive to the overpressure output signal for disconnecting the operational power signal from at least one of the first and second terminals of the electric pump means.   
     
     
       9. An automatic blood pressure gauge, comprising: a neonatal cuff having a relatively small size and an adult cuff having a relatively large size;   inflation means coupled between a reservoir of fluid and a selected one of said neonatal cuff or said adult cuff for inflating said selected cuff with said fluid;   inflation control means coupled to said inflation means for controlling inflation of said selected cuff by said inflation means;   cuff size sensing means included in said inflation means for producing an output signal indicating that the inflation means is connected to a neonatal cuff or to an adult cuff;   a first fluid flow orifice, connected to and in fluid connection with said inflation means and said selected cuff, through which the inflation means provides fluid to the selected cuff at a first rate;   a second fluid flow orifice, connected to and in fluid connection with said inflation means and said selected cuff, through which the inflation means provides fluid to the selected cuff at a second rate, greater than the first rate; and   valve means, coupled to the second fluid flow orifice and responsive to the output signal provided by the cuff size sensing means for selectively opening or closing the second orifice so that fluid can or can not be provided therethrough, respectively, when the selected cuff is an adult cuff or a neonatal cuff, respectively.